In computer storage arrays (also referred to herein as storage systems or storage subsystems), disk partitioning and logical volume management are used to manage physical storage devices such as hard disk drives. In disk partitioning, a single storage device is divided into multiple logical storage units referred to as partitions, thereby treating one physical storage device as if it were multiple disks. Logical volume management provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes. In particular, a volume manager can concatenate, stripe together or otherwise combine regions (a region is a sequence of bytes having a specific length, typically one megabyte) into larger virtual regions that administrators can re-size or move, potentially without interrupting system use.
Small Computer System Interface (SCSI) based storage systems that include storage devices such as SCSI storage devices, Internet Small Computer System Interface (iSCSI) storage devices and Fibre Channel storage devices, typically partition their storage devices into logically addressed portions that can be accessed by host computers. Each of these partitions is called a Logical Unit Number (LUN). LUNs can be regarded as logical drives or “soft partitions”, and can be provisioned by a command issued by management software executing on the storage system. When provisioning storage resources, the management software can create, for example, more than one LUN from one physical storage devices, which would then appear as two or more discrete storage devices to a user. Alternatively, the management software may create a number of LUNs that span several separate storage devices that form a redundant array of independent disks (RAID) array that can appear as discrete storage devices to the user.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.